Internal hernia is a well-known complication after laparoscopic surgery, specially after a Roux-en-Y gastric by-pass. It consists in the protrusion of the small bowel through an acquired mesenteric defect caused by previous surgery. This condition can also be caused by a congenital defect with no previous surgery. The risk of intestinal ischemia and life-threatening complications highlight the importance of an early diagnosis and the frequent need for prompt surgical emergency treatment.

Its incidence is not well established, since specific data on this complication in large clinical trials is lacking.

Mechanisms explaining the development of these hernias include the low rate of postoperative adhesions after minimally invasive surgery and early postoperative mobilization of the patient. The free movement of ileal loops in the abdominal cavity, along with the painless postoperative mobilization, might increase the chance of internal hernia and reduce the adherence of the neo-descending colon to Gerota’s fascia.

Timely recognition of this condition is crucial but not easy. Internal hernias can be asymptomatic or present with aspecific symptoms. Persistent abdominal colicky pain, nausea, and vomiting after colorectal resection should prompt further radiological investigations.

After left-sided colonic resections, usually the first jejunal loops are herniated, therefore no small bowel dilation is seen distally. This fact allows for a laparoscopic approach in most cases. Mortality increases if ischemia is established after a delayed diagnosis.

The mesenteric defect created by surgery can be sutured in the same surgical procedure. However, no strong evidence supports the routine closure of these defects. It is a time-consuming and a technically challenging maneuver, usually at the end of a long surgical procedure. The closure might be performed with a running non-reabsorbable suture, with clips or with fibrin glue. There is a risk of damaging vascular or retroperitoneal structures, and some authors suggest a simple repositioning of the small bowel, with or without omental interposition. Other authors suggest closure of the meso in selected patients only (those with a slim and mobile mesentery).